<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>引出生命周期</title>
    <style>

    </style>
</head>
<body>
<!--准备好一个容器-->
<div id="root"></div>

<!--引入React核心库-->
<script type="text/javascript" src="../0-ReactJs-v16.14.0/react.development.js"></script>
<!--引入React-Dom，用于支持React操作Dom-->
<script type="text/javascript" src="../0-ReactJs-v16.14.0/react-dom.development.js"></script>
<!--引入babel，用于将jsx转为js-->
<script type="text/javascript" src="../0-ReactJs-v16.14.0/babel.min.js"></script>

<script type="text/babel">

    //创建组件
    //生命周期回调函数<=>生命周期钩子函数<=>生命周期函数<=>生命周期钩子
    class Life extends React.Component {

        state = {
            opacity: 1
        }

        death = () => {
            // //清除定时器
            // clearInterval(this.timer)
            //卸载组件
            ReactDOM.unmountComponentAtNode(document.getElementById('root'))
        }

        //组件挂在完毕
        componentDidMount() {
            this.timer = setInterval(() => {
                //获取原状态
                let {opacity} = this.state;
                //减小0.1
                opacity -= 0.1;
                if (opacity <= 0) opacity = 1
                //设置新的透明度
                this.setState({opacity})
            }, 200)
        }

        //组件将要卸载
        componentWillUnmount() {
            //清除定时器
            clearInterval(this.timer)
        }

        //render调用的时机：初始化渲染、状态更新之后
        render() {
            return (
                <div>
                    <h2 style={{opacity: this.state.opacity}}>React学不会怎么办？</h2>
                    <button onClick={this.death}>不活了</button>
                </div>
            )
        }

    }

    //渲染组件到页面
    ReactDOM.render(<Life/>, document.getElementById('root'));

</script>

</body>
</html>
